Pole-change type motor

ABSTRACT

Disclosed is a pole-change type motor that provides a variable-speed (two-pole or four-pole type) operation system capable of reducing the load of the motor of the normal operation system and improving the cooling efficiency. In case of a quick operation, the motor switches over to the two-pole type according to the control of a relay section. At this time, the load of the motor is reduced by offsetting an abnormal magnetic field distribution formed due to the same polarity of adjacent main windings using compensation windings of an opposite polarity. If the quick operation is needed, the motor switches over to the two-pole type, and operates at a high speed to achieve the quick cooling. Then, if a standard operation is possible with the lapse of the predetermined time, the motor switches over to the four-pole type, and operates at a low speed to achieve an effective cooling.

TECHNICAL FIELD

The present invention relates to a motor for a compressor, and moreparticularly to a pole-change type motor.

BACKGROUND ART

Generally, a compressor is a device that compresses refrigerant using arotating force of an internal motor, and is used in a refrigerator, airconditioner, etc.

Especially, as shown in FIG. 1, a motor for a compressor applied in arefrigerator is composed of a stator and a rotor, and can perform only anormal operation (for example, rotation of 3600 rpm) though there is adifference according to the characteristic of the product.

Meanwhile, the representative operation mode of the refrigerator isclassified into a quick operation mode and a standard operation mode.Actually, the time when the refrigerator operates in the quick operationmode is less than 10% of the real use time of the refrigerator, andduring other time, the refrigerator operates in the standard operationmode.

Conventionally, in the standard operation mode, the temperature width tobe adjusted is not so large. However, in the quick operation mode, thetemperature width to be adjusted is large, and thus a quick cooling isperformed by driving the motor at a fixed speed, i.e., at a high speed.This high-speed operation exerts a bad effect on the refrigerator suchas generation of noise, increase of power consumption, strain on theproduct, etc.

Nevertheless, the compressor motor of the refrigerator, irrespective ofthe operation mode, operates at a high speed to match the quick coolingmode.

As shown in FIG. 2, the conventional compressor motor is driven at asingle speed. That is, in case of the quick operation mode, the dutyrate of the motor is set as ‘1’, and the compressor motor iscontinuously driven irrespective of the temperature condition of therefrigerator.

In case of the standard operation mode, the compressor motor is drivento repeat an on/off operation according to a proper duty rate so thatthe refrigerator maintains its set temperature according to thetemperature condition of the refrigerator. At this time, the load of themotor in the quick operation mode is greater than that in the standardoperation mode.

As described above, since the conventional motor for the compressor isdriven at the high speed irrespective of the operation mode, it has alarge power consumption, and generates much noise during operation.Also, the product may be damaged due to the frequent on/off operation ofthe motor, and this causes the life span of the product to be shortened.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to solve the problemsinvolved in the prior art and to provide a pole-change type motor thatcan vary the speed of the motor to provide a variable-speed operationsystem.

In order to accomplish the above-mentioned object, the present inventionprovides a pole-change type motor comprising a rotor, a stator forgenerating a torque of the rotor so as to perform a high-speed orlow-speed operation through a pole change, and a relay section forcontrolling the pole change of the stator.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, other features and advantages of the present inventionwill become more apparent by describing the preferred embodiment thereofwith reference to the accompanying drawings, in which:

FIG. 1 is a view illustrating a conventional motor for a compressor.

FIG. 2 is a graph illustrating an operation state of a conventionalmotor for a compressor.

FIG. 3 is a view illustrating a pole-change type motor for a compressoraccording to the present invention.

FIG. 4 is a view illustrating the structure and winding arrangement of apole-change type motor according to the present invention.

FIG. 5 is a circuit diagram of a control section of a pole-change typemotor according to the present invention.

FIG. 6 is a view illustrating a wiring state of a two-pole operation ofthe motor according to the present invention.

FIG. 7 is a view illustrating a magnet field distribution of a two-poleoperation of the motor according to the present invention.

FIG. 8 is a graph illustrating an abnormal magnetic field distributionof a main winding and compensation for an abnormal magnetic fielddistribution effected by compensation windings according to the presentinvention.

FIG. 9 is a view illustrating a wiring state of a four-pole operation ofthe motor according to the present invention.

FIG. 10 is a view illustrating a magnet field distribution of afour-pole operation of the motor according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the pole-change type motor according to a preferred embodiment ofthe present invention will be described in detail with reference to theannexed drawings.

FIG. 3 is a view illustrating a pole-change type motor for a compressoraccording to the present invention, FIG. 4 is a view illustrating thestructure and winding arrangement of a pole-change type motor accordingto the present invention, and FIG. 5 is a circuit diagram of a controlsection of a pole-change type motor according to the present invention.

Also, FIG. 6 is a view illustrating a wiring state of a two-poleoperation of the motor according to the present invention, FIG. 7 is aview illustrating a magnet field distribution of a two-pole operation ofthe motor according to the present invention, and FIG. 8 is a graphillustrating an abnormal magnetic field distribution of a main windingand compensation for an abnormal magnetic field distribution effected bycompensation windings according to the present invention.

Also, FIG. 9 is a view illustrating a wiring state of a four-poleoperation of the motor according to the present invention, and FIG. 10is a view illustrating a magnet field distribution of a four-poleoperation of the motor according to the present invention.

As shown in FIG. 3, the pole-change type motor according to the presentinvention includes a rotor (reference numeral omitted), a stator(reference numeral omitted) for generating a torque of the rotor so asto perform a high-speed or low-speed operation through a pole change(i.e., from the two-pole type to the four-pole type and vice versa), anda relay section (not illustrated) for controlling the pole change of thestator.

The stator, as shown in FIG. 4, includes first to fourth main windingsM1˜M4 for generating the torque of the rotor by two poles or four poles,first to fourth auxiliary windings S1˜S4 for generating a start torqueand a rotative torque by supplying a magnetic flux orthogonal to amagnetic flux generated by the first to fourth main windings M1˜M4, andfirst and second compensation windings C1 and C2 for compensating for amagnetic flux distortion generated between the same poles of the firstto fourth main windings M1˜M4 during a two-pole operation.

Also, in order to variably adjust the speed of the motor at a low orhigh speed, the relay section changes polarities of the first to fourthmain windings M1˜M4 and the first to fourth auxiliary windings S1˜S4 tothe two poles or four poles, and switches the connection state of thefirst and second compensation windings C1 and C2.

At this time, the relay section includes a first relay section RY1 forswitching to control the on/off operation of the motor, a second relaysection RY2 for switching to change the polarity by changing wiring ofthe first to fourth main windings M1˜M4, a third relay section RY3 forswitching to change the polarity by changing wiring of the first tofourth auxiliary windings S1˜S4, and first and second compensationwindings C1 and C2, and a fourth relay section RY4 for switching tochange wiring of capacitors during the four-pole operation according tothe switching of the third relay section RY3.

According to the present invention, the relay section operates inassociation with a temperature sensor, and if the quick operation isrequired according to a result of temperature sensing, the relay sectioncontrols all the relay sections to switch over to the two-poletermination so that the motor operates with the two poles.

On the contrary, if the load is reduced due to the two-pole operationand thus the quick operation is not required, the relay section controlsthe relay sections to switch over to the four-pole termination so thatthe motor operates with the four poles.

The operation of the pole-change type motor according to the presentinvention as constructed above will now be explained.

First, the operation of the motor in the quick operation mode is asfollows.

Referring to FIG. 5, the first relay section RY1 is turned on, and thesecond and the third relay sections RY2 and RY3 switch over to thetwo-pole termination, respectively. At this time, if the third relaysection RY3 switches over to the two-pole termination, the power issupplied to the first and second compensation windings C1 and C2, whichare connected between the adjacent windings of the same polarity amongthe first to fourth main windings M1˜M4.

During the two-pole operation, the wiring state of the first to fourthmain windings M1˜M4 and the first and second compensation windings C1and C2 is illustrated in FIG. 6.

In this state, the rotor starts to rotate by the start torque of thefirst to fourth main windings M1˜M4 generated by the power supply, andthe motor is driven by the first to fourth main windings M1˜M4 and thefirst and second compensation windings C1 and C2 at a high speed withthe two poles.

At this time, the windings adjacent to each other among the first tofourth main windings M1˜M4 have the same polarity. For example, thefirst and second main windings M1 and M2 have the N pole, and the thirdand fourth main windings M3 and M4 have the S pole. FIG. 7 shows themagnetic field distribution during the two-pole operation.

Because of the above-described magnetic field distribution, there occursan abnormal phenomenon of a space magnetic flux distribution that the Spole is compulsorily created between the first and second main windingsM1 and M2. In this case, since the first compensation windings C1adjacent to the first and second windings M1 and M2 has the N pole, theS pole component of the first and second main windings M1 and M2 isoffset to compensate for the abnormal phenomenon of the space magneticflux distribution.

In the same manner, an abnormal phenomenon of a space magnetic fluxdistribution generated between the third and fourth main windings M3 andM4 is compensated for by the polarity of the second compensation windingC2.

With reference to the graph of FIG. 8, the abnormal phenomenon of thespace magnetic flux distribution generated between the first and secondmain windings M1 and M2 or between the third and fourth main windings M3and M4 during the two-pole operation, i.e., a distortion phenomenon thatthe magnetic flux is rapidly reduced between sixth and seventh slots orbetween 18th and 19th slots.

Accordingly, in order to compensate for the abnormal sine-wave magneticflux due to the distortion phenomenon, the magnetic flux of the first tofourth main windings M1˜M4 and the magnetic flux of the first and secondcompensation windings C1 and C2 are combined to produce a combinedsine-wave magnetic flux, and this causes the efficiency and noisecharacteristics to be improved.

Here, the first and second compensation windings C1 and C2 are connectedin parallel to the first to fourth main windings M1˜M4 in case that theoutput torque is large, while they are connected in series to the firstto fourth main windings M1˜M4 in case that the output torque is small.

During the quick operation, i.e., the two-pole operation, if it isdetected that the quick operation is not required through thetemperature sensing by the temperature sensor, the quick operationshould switch over to the standard operation.

Here, the operation of the motor in the standard operation mode is asfollows.

Referring to FIG. 5, the first relay section RY1 is turned on, and thesecond and the third relay sections RY2 and RY3 switch over to thefour-pole termination, respectively.

At this time, if the third relay section RY3 switches over to thefour-pole termination, the power is supplied to the first to fourthauxiliary windings S1˜S4, and the connection between the first andsecond compensation windings C1 and C2 and the first to fourth mainwindings M1˜M4 is released.

During the four-pole operation, the wiring state of the first to fourthmain windings M1˜M4 and the first to fourth auxiliary windings S1˜S4 isillustrated in FIG. 6.

In this state, the rotor starts to rotate by the start torque of thefirst to fourth main windings M1˜M4 generated by the power supply, andthe motor is driven by the first to fourth main windings M1˜M4 and thefirst to fourth auxiliary windings S1˜S4 at a low speed with the fourpoles.

At this time, as shown in FIG. 10, the mechanical position of the firstto fourth auxiliary windings S1˜S4 is displaced by 90° and the phasethereof is shifted by 90° with respect to the first to fourth mainwindings M1˜M4 to form the four poles.

Also, during the four-pole operation of the motor, the windings adjacentto each other among the first to fourth main windings M1˜M4 have thepolarity opposite to each other. For example, as shown in FIG. 10, thefirst and third main windings M1 and M3 have the N pole, and the secondand fourth main windings M2 and M4 have the S pole, so that the abnormalphenomenon of the space magnetic flux distribution does not occurbetween the main windings.

Accordingly, during the standard operation where the motor operates byfour poles, the connection of the first and second compensation windingsC1 and C2 is released.

Also, according to the present invention, the connection and release ofa starting capacitor Cs connected to the first auxiliary windings S1 iscontrolled through the fourth relay section RY4.

Specifically, in order to increase the start torque of the rotor for apredetermined time through the fourth relay section RY4, the startingcapacitor Cs is connected in parallel to the operation capacitor Cr, andif the predetermined time elapses, the fourth relay section RY4 isturned off.

At this time, while the specified wiring form of the first to fourthmain windings M1˜M4 and the first and second compensation windings C1and C2, and of the first to fourth main windings M1˜M4 and the first tofourth auxiliary windings S1˜S4 have been described and illustrated withreference to the preferred embodiment of the present invention, it willbe apparent that various changes in form and details may be made thereinas needed in circuit design.

INDUSTRIAL APPLICABILITY

As apparent from the above description, the pole-change type motoraccording to the present invention has the effects that if the quickoperation is needed, the motor switches over to the two-pole type andoperates at the high speed to achieve the quick cooling, while if thestandard operation becomes possible with the lapse of the predeterminedtime, the motor switches over to the four-pole type and operates at thelow speed to achieve an effective cooling.

1. A pole-change type motor comprising: a rotor; a stator for generatinga torque of the rotor so as to perform a high-speed or low-speedoperation of the motor through a pole change; and a relay section forcontrolling the pole change of the stator according to a load on themotor, the relay section comprising: a first relay section for switchingto control an on/off operation of the motor; a second relay section forswitching to change the pole of the stator from a two-pole type to afour-pole type and vice versa by changing wiring of the first and fourthmain windings; a third relay section for switching to change a polarityby changing wiring of the first to fourth auxiliary windings, and thefirst and second compensation windings; and a fourth relay section forswitching to control a start torque during a four-pole operationaccording to the switching operation of the third relay section.
 2. Thepole-change type motor of claim 1, wherein the stator comprises: firstto fourth main windings for generating the torque of the rotor by twopoles or four poles; first to fourth auxiliary windings for generating astart torque and a rotative torque by supplying a magnetic fluxorthogonal to a magnetic flux generated by the first to fourth mainwindings; and first and second compensation windings for compensatingfor a magnetic flux distortion generated between the same poles of thefirst to fourth main windings during a two-pole operation.
 3. Thepole-change type motor of claim 2, wherein the first and secondcompensation windings are connected between the adjacent windings of thesame polarity among the first to fourth main windings during thetwo-pole operation.
 4. The pole-change type motor of claim 2, whereinthe first and second compensation windings are disconnected from thefirst to fourth main windings during a four-pole operation.
 5. Thepole-change type motor of claim 2, wherein the first and secondcompensation windings compensate for a magnetic flux distortiongenerated in the first to fourth main windings.
 6. The pole-change typemotor of claim 1, wherein the third relay section switches over to thefirst and second compensation windings during the two-pole operation. 7.The pole-change type motor of claim 1, wherein the third relay sectionswitches over to the first to fourth auxiliary windings during thefour-pole operation.
 8. The pole-change type motor of claim 1, whereinthe fourth relay section is turned on for a predetermined time duringthe four-pole operation according to the switching operation of thethird relay section.
 9. The pole-change type motor of claim 1, the starttorque according to the switching operation of the fourth relay sectionis controlled by changing wiring of a capacitor connected to the firstauxiliary winding during the four-pole operation.
 10. The pole-changetype motor of claim 1, wherein the wiring of first to fourth mainwindings is changed to form four poles through the second relay sectionduring a standard operation of the rotor.
 11. The pole-change type motorof claim 1, wherein wiring of first to fourth main windings is changedto form two poles through a second relay section during a quickoperation of the rotor.
 12. The pole-change type motor of claim 1,wherein during the high-speed operation of the rotor, the rotorinitially operates by four poles during a predetermined number ofrotations, and with the lapse of the predetermined number of rotations,the rotor operates by two poles through the pole change.
 13. Apole-change type motor comprising: a rotor; a stator including first tofourth main windings for generating a torque of the rotor by two polesor four poles, first to fourth auxiliary windings for smoothly effectinggeneration of a start torque and a rotative torque through aninteraction by supplying a magnetic flux orthogonal to a magnetic fluxgenerated by the first to fourth main windings, and first and secondcompensation windings for compensating for a magnetic flux distortiongenerated between the same poles of the first to fourth main windingsduring a two-pole operation; and a relay section for changing a polarityof the first to fourth main windings from the two poles to the fourpoles and vice versa, and switching a connection state of the first andsecond compensation windings.
 14. A pole-change type motor comprising: arotor; a stator including first to fourth main windings for generating atorque of the rotor by two poles or four poles, first to fourthauxiliary windings for smoothly effecting generation of a start torqueand a rotative torque through an interaction by supplying a magneticflux orthogonal to a magnetic flux generated by the first to fourth mainwindings, and first and second compensation windings for compensatingfor a magnetic flux distortion generated between the same poles of thefirst to fourth main windings during a two-pole operation; and a relaysection including a first relay section for switching to control anon/off operation of the motor, a second relay section for controlling tochange a polarity of the stator from a two-pole type to a four-pole typeand vice versa by changing wiring of the first to fourth main windings,a third relay section for controlling to apply a power to the first andsecond compensation windings during the two-pole operation and to applythe power to the first to fourth auxiliary windings during the four-poleoperation, and a fourth relay section for controlling a connection of acapacitor to increase the start torque of an initial operation for apredetermined time during the four-pole operation.
 15. A pole-changetype motor comprising: a rotor; a stator for generating rotor torque soas to perform a high-speed or low-speed motor operation depending on aselected number of poles; and a relay section for selecting the numberof stator poles according to a load on the motor, wherein the relaysection comprises: a first relay for controlling an on/off operation ofthe motor; a second relay for selecting the number of the stator polesby changing wiring of the main windings according to the load of themotor; and a third relay for selecting the number of the stator poles byselectively changing wiring of the auxiliary windings and thecompensation windings according to the load of the motor.
 16. Thepole-change type motor of claim 15, wherein the stator comprises: aplurality of main windings for generating the rotor torque depending onthe selected number of stator poles; a plurality of auxiliary windingsfor supplying a magnetic flux orthogonal to a magnetic flux generated bythe main windings; and a plurality of compensation windings forcompensating for a magnetic flux distortion generated between same polesof the main windings.
 17. The pole-change type motor of claim 15,wherein the third relay switches over to the compensation windings iftwo stator poles are selected.
 18. The pole-change type motor of claim15, wherein the third relay switches over the auxiliary windings if fourstator poles are selected.
 19. The pole-change type motor of claim 15,further comprising a fourth relay between the third relay and theauxiliary windings.
 20. A pole-change type motor comprising: a rotor; astator including a plurality of main windings for generating rotortorque depending on a number of stator poles, a plurality of auxiliarywindings for supplying a magnetic flux orthogonal to a magnetic fluxgenerated by the main windings, and a plurality of compensation windingsfor compensating for a magnetic flux distortion generated between samepoles of the main windings; and a relay section changing wiring of themain windings and alternatively switching to the auxiliary windings andthe compensation windings.
 21. The pole-change type motor of claim 20,wherein the relay section changes the wiring of the main windings andalternatively switches to the auxiliary windings and the compensationwindings according to a load on the motor.
 22. The pole-change typemotor of claim 20, wherein the relay section connects the main windingswith the compensation windings in parallel or in series according to atorque intensity generated by the stator.
 23. The pole-change type motorof claim 20, wherein the relay section comprises: a first relay forcontrolling an on/off operation of the motor; a second relay forchanging wiring of the main windings; and a third relay foralternatively switching to the auxiliary windings and the compensationwindings.
 24. The pole-change type motor of claim 20, wherein the relaysection switches over to the compensation windings during a two-poleoperation.
 25. The pole-change type motor of claim 20, wherein the relaysection switches over to the auxiliary windings during a four-poleoperation.